Thanks for taking the time to share your ideas. Truthfully, I haven't quite decided exactly how much magic/science to include - I'm just mixing-and-matching ideas as they pop up until I find a combination that kinda fits.
I do like your ideas about reskinning humans by using the race mechanics as backgrounds. This somewhat resembles the rules in a link posted earlier and seems to be the simplest way to limit the Mos Eisley Cantina-effect without losing the variety of built-in race differentiating mechanisms.